Natasha MacBryde was a beautiful, clever girl hoping to be a vet or paediatrician, who seemed perfectly happy at school until a few months after she turned 15, when she suddenly wanted to dye her hair brown.

Her mother Jane discovered, over the next few weeks, that Tasha (as the family called her) had become the target of nasty messages from fellow pupils on Formspring, a website (which has since closed) where the senders could remain anonymous.

She was further upset at being rejected by a boy she liked. On the evening before Valentine's Day, she looked at Formspring one last time - with its latest, poisonous message - then slipped out of the house and walked to a nearby railway track. She was hit by a train.

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